Method of using a lifting post for cleaning a net of a sea pen

Abstract

Method for air drying a fouled net portion of a net comprising the fouled net portion and a clean net portion in a circular sea pen. The method includes the steps of: a) fastening lifting posts to the pen on a drying side; b) attaching slidingly internal ropes to the net; c) fitting winches to the lifting posts on a drying side; d) connecting an energy source to the winches; e) releasing a suitable part of a clean net portion from a handrail; f) fastening the internal rope to a winch; g) bringing a part of the fouled net portion into the air by pulling the internal rope with the winch; h) fastening a part of the fouled net portion to the handrail; and i) repeating steps e)-h) until the complete fouled net portion is lifted into the air. The invention regards also lifting posts to carry out the method.

Claims

1. A method for air drying a fouled net portion of a net comprising the fouled net portion and a clean net portion, said net being positioned in a circular sea pen, wherein the method comprises the steps of: a) providing a number of lifting posts and fastening the lifting posts to floating concentric rings of the circular sea pen; b) providing the net with internal ropes, each rope slidingly attached to the net; c) providing a number of detachable winches, each winch adapted to be fitted to a fastening organ of the lifting post, and fitting the winches on the side of the sea pen to which the fouled net portion is to be air dried; d) providing an energy source for the winches and connecting the energy source to the winches; e) releasing a suitable part of the clean net portion from a handrail; f) fastening one of the internal ropes to one of the winches; g) bringing a part of the fouled net portion into the air by pulling the fastened internal rope with the winch to which the internal rope is fastened; h) fastening a part of the fouled net portion to the handrail; and i) repeating steps e)-h) until the complete fouled net portion is lifted into the air.

2. The method according to claim 1, where the method further comprises lifting the base of the fouled net portion to the surface to release the fouled net portion from a bottom ring prior to step e).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following is described an example of a preferred embodiment illustrated in the accompanying figures, wherein:

(2) FIG. 1 shows a photo of a model of a sea pen where the clean net portion is fastened to one side of the sea pen according to the invention;

(3) FIG. 2 shows the same as in FIG. 1, but viewed from the opposite side of the model of the sea pen;

(4) FIGS. 3-5 shows from the same view as FIG. 2, a sequence of how the net is lifted at one side and released at the opposite side;

(5) FIG. 6 shows a principal sketch of how each lifting station according to the invention is provided with hydraulic power from a central hydraulic power unit;

(6) FIG. 7A shows a lifting post that is retrofittable to a plastic bracket of a sea pen;

(7) FIG. 8 shows in a larger scale a bracket fastened to a plastic buoyancy element;

(8) FIG. 9 shows in the same scale as FIG. 8, the bracket alone from an opposite direction;

(9) FIG. 10 shows in a smaller scale the same as FIG. 8 and a detachable stem body;

(10) FIG. 11A-B show schematically from above two nets before and after being sewn together along their headlines; and

(11) FIG. 12A-E show schematically a side view of a sea pen and a sequence of replacing a fouled net portion with a clean net portion.

DETAILED DESCRIPTION OF THE DRAWINGS

(12) In the drawings, the reference numeral 1 indicates a lifting post for a sea pen 2 (see FIGS. 7, 10 and 12A-E). The lifting post 1 comprises an elongated stem 11 with a base portion 10 and an opposite free end portion 19. The stem 11 is provided with a fastening organ 13 for a detachable winch 3, schematically shown in FIG. 6, between the base portion 10 and the free end portion 19, and a pull portion 15 between the fastening organ 13 and the free end portion 19. The base portion 10 is provided with a first fastening means 100 for connecting the lifting post 1 to a plastic bracket 21 connecting two floating concentric plastic rings 23 of a circular sea pen 2. The stem 11 is shown with a second fastening means 120 for connecting the lifting post 1 to a pillar 220 or a handrail 222 of a railing of the circular sea pen 2. A gangway (not shown) is positioned on top of the plastic rings 23.

(13) An alternative embodiment for the first fastening means 100 are shown in FIGS. 8-10. The fastening means 100 comprises an upper clamp bracket 150 and a lower clamp bracket 190. As shown in FIG. 8, the upper clamp bracket 150 and the lower clamp bracket 190 surround the plastic bracket 21. The upper clamp bracket 150 and the lower clamp bracket 190 are joined by a bolt connection 160. The upper clamp bracket 150 is provided with a fastener 155 shown as an anchor bar 155. The anchor bar 155 is positioned at the opposite end of the upper clamp bracket 150 relative to the stem 11. A sling strap or similar means may be fastened to the anchor bar 155. A bottom ring (not shown) may be fastened to the clamp bracket 150 via a connection element (not shown). The bottom ring provides a counter weight when a net 4 is lifted at the stem 11.

(14) A locator tube 165 is positioned within the plastic bracket 21 to facilitate the assembly of upper clamp bracket 150 and the lower clamp bracket 190 around the plastic bracket 21 (see FIG. 8). A guide bar 167 (see FIG. 9) is located within the lower clamp bracket 190 and is positioned within the locator tube 165 when the fastening means 100 is assembled. Prior to providing the sea pen 2 with the clamp brackets 150, 190, the connection element for the bottom ring may be guided through the locator tube 165.

(15) The base portion 10 further comprises a stem holder 110 provided with an open end portion 119. The second fastening means 120 is fixed to the stem holder 110. As shown in FIG. 10, the stem 11 further comprises a detachable elongated stem body 111. The lower portion of the stem body 111 is shown to fit inside the stem holder 110. The stem body 111 is at the free end portion 19 shown provided with a sheave 16. An internal rope (not shown) for pulling a net 4 may pass over the pull portion 15 or the sheave 16. The stem body 111 further comprises the fastening organ 13. The stem body 111 may further comprise the pull portion 15 as shown in FIG. 10.

(16) The net 4 comprises two circular nets 41 and 43 that are sewn together along a headline 410, 430 of each net 41, 43 as shown schematically and from above in FIGS. 11A and 11B (see also FIG. 4). About half of the headline 410 of the first circular net 41 is sewn together with about half of the headline 430 of the second net 43.

(17) FIGS. 12A-12E show schematically the sequence of replacing a fouled net portion 42 with a clean net portion 44 of the net 4. The fouled net portion 42 comprises a front wall 421, a base 423 and a back wall 427. The base 423 is divided in a first half base 424 and a second half base 425. The clean net portion 44 comprises a front wall 441, a base 443 and a back wall 447. The base 443 is divided in a first half base 444 and a second half base 445.

(18) Initially, the clean net portion 44 is fully exposed to air. Organisms which previously attached to the clean net portion 44, are killed by desiccation, exposure to fresh water such as rain, and sun radiation. The clean net portion 44 is fixed to the handrail 222 by lashings (not shown).

(19) A detachable winch 3 (see FIG. 6) is fitted to each lifting post 1 that will be engaged in the operation. Typically, there will be four lifting posts 1 side by side at the opposite side of the sea cage 2 relative to the side where the clean net portion 44 is positioned.

(20) A first set of internal ropes (not shown) of the fouled net portion 42 are put onto the winches 3 and the first lift is commenced. The front wall 421 of the fouled net portion 42 is brought into the air by the first lift. The front wall 421 of the fouled net portion 42 is fastened to the handrail 222.

(21) Tail ends of a second set of internal ropes have hit the surface after the first lift. The tail ends of the second set of internal ropes are put onto the winches 3. The second lift is then commenced. In this second lift, half the base 423, 424 of the fouled net portion 42 is brought into the air. This part of the base 423, 424 of the fouled net portion 42 is fastened to the handrail 222. The front wall 441 of the clean net portion 44 is dropped into the water.

(22) Tail ends of a third set of internal ropes have hit the surface after the second lift. The tail ends of the third set of internal ropes are put onto the winches 3. The third lift is then commenced. In this third lift, the second half of the base 423, 425 of the fouled net portion 42 is brought into the air. This second half 425 of the base 423 of the fouled net portion 42 is fastened to the handrail 222. The part of the clean net portion 44 that will form half of the base 443, 444 of the enclosure after operation is dropped into the water.

(23) Tail ends of a fourth set of internal ropes have hit the surface after the third lift. The tail ends of the fourth set of internal ropes are put onto the winches 3. The fourth and last lift is then commenced. In this fourth lift, the back wall 427 of the fouled net portion 42 is brought into the air. The back wall of 427 the fouled net portion 42 is fastened to the handrail 222. The remaining parts, e.g. a second portion 445 of the bottom portion 443 and the back wall 447 of the clean net portion 44 are dropped into the water.

(24) FIGS. 1-5 show the same sequence as described above.

(25) It is important to the method that lifting the net 4 is co-ordinately carried out at all four lifting posts 1 and at the same time to spread the load on the net 4 and the buoyancy element, i.e. the floating concentric plastic rings 23.

(26) The number of lifts may deviate from the description above depending on the size of the net 4 and other factors. The number of lifting posts 1 may deviate from four.

(27) FIG. 6 shows schematically a hydraulic system 5 for operating the winches 3 attached to the lifting posts 1. The hydraulic system 5 comprises a hydraulic power unit 51, a manifold 53 and a number of valves 55. The valves 55 may be operated by a pedal (not shown) for convenience. Each valve 55 is connected to a detachable winch 3 such that the winch 3 is activated by opening the valve 55 by the pedal. The hydraulic system 5 comprises in addition necessary hydraulic feed lines and hydraulic return lines for connecting the power unit 51, the manifold 53 and the valves 55. The power unit 51 may be positioned onboard a vessel (not shown). The manifold 53 may be positioned onboard the vessel or positioned on the gangway. After the clean net portion 44 has replaced the fouled net portion 42, the hydraulic system 5 is disassem-bled and the winches 3 disconnected from the lifting posts 1. The stem bodies 111 are detached from their stem holders 110. The stem bodies 111, winches 3 and hydraulic system 5 may then be moved to another sea cage 2 or utilized at the opposite side of the sea cage 2 when it is again necessary to replace the fouled net portion 42.

(28) It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb “comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.

(29) The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.